objective c - UIPanGestureRecognizer on MKMapView?

Question

I would like to add some logic when user moves with map view i. e. he does a pan touch. But when I add the gesture recognizer and I want to log the touch, nothing happens. When I try it in another view controller and add the recognizer to controller's view then it works ok.

Here's my code (map view is a property of application delegate because I need to do some other things with it even if it isn't visible):

- (void)viewDidLoad
{
    ...
    UIPanGestureRecognizer *panGesture = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(showPan)];
    [appDelegate.mapView addGestureRecognizer:panGesture];
    [panGesture release];
}

- (void)showPan
{
    NSLog(@"pan!");
}

I use latest iOS 4.2.1

Thanks for any advice.

Answer 1

Ok, because no one knew, I had to spent one Apple technical support consult for it. ;o)

Because MKMapView evidently has its own recognizers to interact with user, you have to adhere to the UIGestureRecognizerDelegate protocol and implement (BOOL)gestureRecognizer:shouldRecognizeSimultaneouslyWithGestureRecognizer: like this:

- (void)viewDidLoad
{
    ...
    UIPanGestureRecognizer *panGesture = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(showPan)];
    panGesture.delegate = self;
    [appDelegate.mapView addGestureRecognizer:panGesture];
    [panGesture release];
}

- (void)showPan
{
    NSLog(@"pan!");
}

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer {   
    return YES;
}

Then it works like a charm.